This invention relates to an improvement in processes for the preparation of higher secondary and tertiary alkanols from olefins via sulfation and hydrolysis reactions. More particularly, this invention relates to a method for the enhanced recovery of alkanols in high selectivity from the crude reaction mixture of such a process.
The hydration of higher (C.sub.6 to C.sub.20) olefins to alkanols of corresponding carbon number is known to be accomplished by a process in which the olefins undergo sulfation by reaction with concentrated sulfuric acid to yield monoalkylsulfuric acids (alkyl sulfate esters) which are then hydrolyzed to the desired alkanols. Markovnikov addition yields secondary or tertiary alkanols. C.sub.6 to C.sub.20 secondary and tertiary alkanols are commercial materials having estalished utility in a variety of applications, for instance, as plasticizers and as intermediates in the synthesis of surfactants and lubricants.
A major limitation on the efficiency of alkanol preparation in this manner relates to the formation during the sulfation and hydrolysis reactions of a number of by-product compounds. For instance, the crude reaction mixture obtained following hydrolysis contains, in addition to alkanol and olefin, a substantial quantity of such by-products as olefin dimers and polymers, dialkylethers, alkyl sulfates, dialkyl sulfates, and alkyl sulfonates. Overall, by-product make in a process having an acceptable rate and conversion of olefin to alkanol typically accounts for a processing loss, measured in terms of utilization of olefin starting material, that is on the order of 3 to 15 percent. It is an object of this invention to provide an improvement in alkanol preparation processes which results in a low net production of such by-products. It is a further object of this invention to provide improvement in alkanol preparation processes which results both in a low net production of by-products and in an acceptably high yield of alkanol.